New Alzheimer's study shows promise

Scientists caution that findings need verification

A new study is generating hope — and international attention — that a simple blood test may be able to determine who will develop Alzheimer’s disease.

The test would be a major milestone because current methods of detecting the progressive neurological affliction are expensive and invasive. A relatively low-tech alternative like a blood test has the potential to expand the number of people who could participate in the clinical trials necessary to create new Alzheimer’s drugs and therapies.

But the goal of better research is tempered by some concern, especially among medical ethicists, that predicting the onset of such a devastating disease in specific patients could be harmful without an effective treatment — something not available yet.

The study, published online Sunday in the journal Nature Medicine, was conducted by researchers at Georgetown University in Washington, D.C., and the University of Rochester in New York. It found low levels of certain lipid fats in the blood of 28 seniors, all age 70 or older, who developed Alzheimer’s or its precursor, mild cognitive impairment. About 500 seniors who did not show signs of the disease had normal to high levels of those lipids.

Looking for these 10 markers, then, could provide an early warning of who is on the path to developing Alzheimer’s — the sixth-leading cause of death in the United States and likely to grow as baby boomers age. By comparing the blood samples of people with the disease and those who are unaffected, the researchers believe scientists and doctors can predict onset “within a two- to three-year time frame with over 90 percent accuracy.”

Dr. Mark Mapstone, the paper’s lead author, said Monday that the public should not expect to start getting blood tests for Alzheimer’s anytime soon. He said more research is needed to verify that the initial results are valid — and whether the analysis can be effective for people in their 40s and 50s. Earlier detection could enable patients and their health providers to have more options for preventing, halting or slowing the disease.

“We think that the value of this screening method, right now, is for research. By no means do we feel this should be something out there being used to screen patients at the clinic,” Mapstone said.

Alzheimer’s is a form of dementia, and Mapstone said he does not know if the 10 markers isolated in his team’s study could be used to predict other types of memory loss.

Still, the blood-test announcement is getting lots of attention from the Alzheimer’s research community and from a public eager for any bit of news that points to progress in vanquishing a scourge that robs millions of their most precious memories.

Dr. Paul Aisen, director of the Alzheimer’s Disease Cooperative Study at UC San Diego, said Mapstone and his colleagues have made a notable discovery.

“It is very interesting and, potentially, very important,” he said. “But it is important to note that it has to be evaluated in different populations so that we have some confidence in its utility. There have been many predictive markers developed for Alzheimer’s over the years that have not stood the test of time.”

Developed in 1991, Aisen’s group at UC San Diego works with the National Institute on Aging to conduct Alzheimer’s studies nationwide. Since its inception, it has conducted 23 Alzheimer’s drug studies, including an ongoing trial to test solanezumab, a compound that attacks a protein called amyloid beta which is believed to interfere in brain cell function.

Having a cheap way to detect Alzheimer’s in its formative stages, Aisen said, would give researchers a way to do studies of much larger populations than is currently possible with existing technology.

But a test that can predict with near certainty who will develop the disease also comes with a set of complex moral questions.

Though researchers such as Mapstone and Aisen would not condone widespread use of such a test on patients until effective treatments have been developed, Lawrence Hinman, a professor of philosophy at the University of San Diego, noted that commerce often goes its own way.

He said if a company were to make and sell a test based on this new research, it could have devastating effects on people who are unprepared to receive the diagnosis.

“I would be particularly concerned with the way in which this would impact a person’s view of themselves as well as other people’s view of them,” Hinman said. “When someone receives this kind of news, you certainly would like to see the support services beyond just notification.”

Mapstone said while it is technically possible for a commercial company to use the research as a jumping-off point to make a blood test, both Georgetown and the University of Rochester have taken steps to make sure they don’t simply crib the 10 markers listed in the paper.

“The institutions have applied for patents on these biomarkers,” Mapstone said.

Meanwhile, there is still much work to do in the laboratory.

The five-year study collected blood samples from 525 people age 70 or older. One hundred of them were recruited in Irvine and the balance came from Rochester. All were subject to memory testing at the beginning of the study and 46 were found to already meet the criteria for Alzheimer’s or mild cognitive impairment and were excluded from comparison.

Mapstone said that, because there were only 28, out of more than 500, who were diagnosed during the study period, it will be necessary to test many more people from different backgrounds to see if the 10 lipids are still predictive.

“Our subjects were primarily Caucasians of middle to upper income and with higher levels of education,” Mapstone said. “We need to get more diversity in terms of race, ethnicity and socioeconomic status.”

Rather than run a whole new five-year study with many more participants, the researcher said the preferred method for moving forward and validating the initial results is to do what’s called a retrospective study that examines blood samples given to other labs for other studies. Mapstone said he has already been contacted by many researchers who have volunteered samples that might help get the job done.

“Now this whole thing has to stand up to the rigor of somebody else’s lab showing the same thing, and we’re cautiously optimistic that it will,” Mapstone said.